Project Summary Improved understanding of community level determinants of perinatal health disparities is a research priority for national health agencies. Community violence may contribute to adverse maternal and infant outcomes and may be instrumental in explaining disparities in perinatal health by race/ethnicity and foreign-born status. However, research has been substantially hampered by cross-sectional designs and methods that cannot disentangle the effects of community violence from other highly correlated determinants of health. Thus, there is a critical need for rigorous research to determine the effects of different aspects of community violence, both predictable overall levels and unexpected acute changes, and to identify underlying psychological, behavioral and biological mechanisms of effect that contribute to maternal and infant health and disparities. The overall objective of this application is to test the central hypothesis that community violence increases the burden of and disparities in maternal and infant health outcomes, and that potentially modifiable psychological (mental health, social support), behavioral (substance use) and biological (maternal infections and conditions) mechanisms underlie these effects. This hypothesis is supported by preliminary analyses that find trimester-specific violence is related to preterm delivery, with the strongest effects among African Americans. The central hypothesis will be addressed using data-adaptive quasi-experimental matching and fixed-effects methods and a rich covariate set to accurately determine the effects of community violence on maternal and infant health. Analyses will be conducted with over 6 million mothers and infants from statewide data on California (2005-2017) and survey- based data on a representative sample of over 72,000 of these mothers and infants. The proposed research will address the following specific aims: (1) Quantify the impacts of acute changes in community violence on maternal and infant health disparities, and psychological, behavioral and biological mechanisms that explain the impacts; (2) Determine the effects of the overall levels of community violence on maternal and infant health disparities, and psychological, behavioral and biological mechanisms that underlie the effects. The work is innovative in (a) distinguishing effects of overall levels of violence from acute changes in violence, (b) examining potentially modifiable mechanisms, and (c) estimating population effects of potential interventions on violence and the mediators. The research is expected to increase scientific understanding of the broader impacts of violence and its role in shaping health disparities. In addition, this work is expected to identify the mechanisms that explain the effects of violence on maternal and infant health, uncovering why racial/ethnic groups such as Latinas appear to be protected, and potentially suggesting alternative points for intervention. Together, these findings are expected to have an important positive impact because they will reframe violence as affecting health and racial/ethnic disparities broadly and thereby motivate interventions to reduce violence and mitigate its downstream effects, which will enhance health and reduce health disparities in the US.